This invention relates to a semiconductor device having a plurality of conductor layers.
In the manner which will later be described more in detail, a conventional semiconductor device comprises a semiconductor substrate, a first insulator layer, a first conductor layer, a second insulator layer, and a second conductor layer. The semiconductor substrate has a principal surface. The first insulator layer overlies the principal surface and has a first upper insulator surface. The first conductor layer overlies the first upper insulator surface and has a first upper conductor surface leaving a surrounding area of the first upper insulator surface. The second insulator layer overlies the first upper conductor surface and the surrounding area and has a second upper insulator surface. The second insulator layer has a recessed surface which defines a contact perforation exposing a predetermined area of said first upper conductor surface. The second conductor layer comprises a primary conductor film and a secondary conductor film. The primary conductor film overlies the second insulator surface, the recessed surface in a predetermined area and has a primary upper surface. The secondary conductor film overlies the primary upper surface.
The secondary conductor film is connected to the first conductor layer through the primary conductor film. The primary conductor film has a first resistance value which is high. Consequently, a resistance value at a connection point of the first and the second conductor layers is high.
Another conventional semiconductor device is disclosed in Japanese Unexamined Patent Prepublication (Kokai) No. 137231/1983. This conventional semiconductor device comprises a semiconductor substrate, a first insulator layer, a first conductor layer, a second insulator layer, and a second conductor layer. The semiconductor substrate has a principal surface. The first insulator layer overlies the principal surface and has a first upper insulator surface. The first conductor layer overlies the first upper insulator surface and has a first upper conductor surface leaving a surrounding area of the first upper insulator surface. The second insulator layer overlies the first upper conductor surface and the surrounding area and has a second upper insulator surface. The second insulator layer has a first recessed surface which defines a first contact perforation exposing a predetermined area of the first upper conductor surface. The second conductor layer comprises a primary conductor film and a secondary conductor film. The primary conductor film overlies a second upper insulator surface and has a primary upper surface. The primary conductor film has a second recessed surface which defines a second contact perforation exposing, in combination with the first contact perforation, the predetermined area of the first upper conductor surface. The secondary conductor film overlies the primary upper surface, the first and the second recessed surfaces, and the predetermined area. Namely, the secondary conductor film is directly connected to the first conductor layer. Consequently, a resistance value at a connection point of the first and the second conductor layers is low. It will be assumed that the secondary film is made of gold. In this event, the secondary film can not be formed on the second recessed surface by electroplating without a conductor film on the second recessed surface.